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Converterless transmission shift control system

  • US 7,326,149 B2
  • Filed: 11/05/2004
  • Issued: 02/05/2008
  • Est. Priority Date: 11/05/2004
  • Status: Active Grant
First Claim
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1. A control method for controlling speed ratio shifts in a multiple-ratio converterless transmission for an automotive vehicle powertrain wherein an internal combustion engine is connected directly to torque input elements of the transmission, the transmission having multiple pressure-actuated friction elements, a speed ratio change in the transmission being effected by engaging a pressure actuator for an oncoming friction element and releasing a pressure actuator for an off-going friction element, the method comprising the steps of:

  • increasing actuating pressure for the oncoming friction element during a torque phase of a power-on upshift;

    detecting slip speed of an actuator for the oncoming friction element at the beginning of an inertia phase of the power-on upshift;

    controlling slip speed of the oncoming friction element using closed loop control triggered by detection of slip speed of the actuator for the oncoming friction element; and

    increasing pressure of the actuator for the oncoming friction element at the end of the closed loop control as slip of the oncoming friction element becomes approximately zero.

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